vendredi 4 novembre 2016

In a paper published yesterday in the journal Science, the ASACUSA experiment at CERN reported new precision measurement of the mass of the antiproton relative to that of the electron. This result is based on spectroscopic measurements with about 2 billion antiprotonic helium atoms cooled to extremely cold temperatures of 1.5 to 1.7 degrees above absolute zero. In antiprotonic helium atoms an antiproton takes the place of one of the electrons that would normally be orbiting the nucleus. Such measurements provide a unique tool for comparing with high precision the mass of an antimatter particle with its matter counterpart. The two should be strictly identical.

"A pretty large number of atoms containing antiprotons were cooled below minus 271 degrees Celsius. It’s kind of surprising that a ‘half-antimatter’ atom can be made so cold by simply placing it in a refrigerated gas of normal helium," said Masaki Hori, group leader at the ASACUSA collaboration.

Image above: The ASACUSA experiment at CERN today reported new precision measurement of the mass of the antiproton relative to that of the electron. (Image: Sophia Bennett/ CERN).

Matter and antimatter particles are always produced as a pair in particle collisions. Particles and antiparticles have the same mass and opposite electric charge. The positively charged positron, for example, is an anti-electron, the antiparticle of the negatively charged electron. Positrons have been observed since the 1930s, both in natural collisions from cosmic rays and in particle accelerators. They are used today in hospital in PET scanners. However, studying antimatter particles with high-precision remains a challenge because when matter and antimatter come into contact, they annihilate – disappearing in a flash of energy.

CERN’s Antiproton Decelerator is a unique facility delivering low-energy antiproton beams to experiments for antimatter studies. In order to make measurements with these antiprotons, several experiments trap them for long periods using magnetic devices. ASACUSA’s approach is different as the experiment is able to create very special hybrid atoms made of a mix of matter and antimatter: these are the antiprotonic helium atoms composed of an antiproton and an electron orbiting a helium nucleus. They are made by mixing antiprotons with helium gas. In this mixture, about 3% of the antiprotons replace one of the two electrons of the helium atom. In antiprotonic helium, the antiproton is in orbit around the helium nucleus, and protected by the electron cloud that surrounds the whole atom, making antiprotonic helium stable enough for precision measurements.

The measurement of the antiproton’s mass is done by spectroscopy, by shining a laser beam onto the antiprotonic helium. Tuning the laser to the right frequency causes the antiprotons to make a quantum jump within the atoms. From this frequency the antiproton mass relative to the electron mass can be calculated. This method has been successfully used before by the ASACUSA collaboration to measure with high accuracy the antiproton’s mass. However, the microscopic motion of the antiprotonic helium atoms introduced a significant source of uncertainty in previous measurements.

The major new achievement of the collaboration, as reported in Science, is that ASACUSA has now managed to cool down the antiprotonic helium atoms to temperatures close to absolute zero by suspending them in a very cold helium buffer-gas. In this way, the microscopic motion of the atoms is reduced, enhancing the precision of the frequency measurement. The measurement of the transition frequency has been improved by a factor of 1.4 to 10 compared with previous experiments. Experiments were conducted from 2010 to 2014, with about 2 billion atoms, corresponding to roughly 17 femtograms of antiprotonic helium.

According to standard theories, protons and antiprotons are expected to have exactly the same mass. To date, no difference has been found between their masses, but pushing the precision limits of this comparison is a very important test of key theoretical principles such as the CPT symmetry. CPT is a consequence of basic symmetries of space-time, such as its isotropy in all directions. The observation of even a minute breaking of CPT would call for a review of our assumptions about the nature and properties of space-time.

The ASACUSA collaboration is confident that it will be able to further improve the precision of antiproton’s mass by using two laser beams. In the near future, the start of the ELENA facility at CERN will also allow the precision of such measurements to be improved.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

For more information about European Organization for Nuclear Research (CERN), Visit: http://home.cern/

What would we do if we discovered a large asteroid on course to impact Earth? While highly unlikely, that was the high-consequence scenario discussed by attendees at an Oct. 25 NASA-FEMA tabletop exercise in El Segundo, California.

The third in a series of exercises hosted jointly by NASA and FEMA -- the Federal Emergency Management Agency -- the simulation was designed to strengthen the collaboration between the two agencies, which have Administration direction to lead the U.S. response. “It’s not a matter of if -- but when -- we will deal with such a situation,” said Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate in Washington. “But unlike any other time in our history, we now have the ability to respond to an impact threat through continued observations, predictions, response planning and mitigation.”

The exercise provided a forum for the planetary science community to show how it would collect, analyze and share data about a hypothetical asteroid predicted to impact Earth. Emergency managers discussed how that data would be used to consider some of the unique challenges an asteroid impact would present—for preparedness, response and public warning.

“It is critical to exercise these kinds of low-probability but high-consequence disaster scenarios,” FEMA Administrator Craig Fugate said. “By working through our emergency response plans now, we will be better prepared if and when we need to respond to such an event.”

Exercise attendees included representatives from NASA, FEMA, NASA’s Jet Propulsion Laboratory, the Department of Energy’s National Laboratories, the U.S. Air Force, and the California Governor’s Office of Emergency Services.

The exercise simulated a possible impact four years from now -- a fictitious asteroid imagined to have been discovered this fall with a 2 percent probability of impact with Earth on Sept. 20, 2020. The simulated asteroid was initially estimated to be between 300 and 800 feet (100 and 250 meters) in size, with a possibility of making impact anywhere along a long swath of Earth, including a narrow band of area that crossed the entire United States.

In the fictitious scenario, observers continued to track the asteroid for three months using ground-based telescope observations, and the probability of impact climbed to 65 percent. Then the next observations had to wait until four months later, due to the asteroid’s position relative to the sun. Once observations could resume in May of 2017, the impact probability jumped to 100 percent. By November of 2017, it was simulated that the predicted impact would occur somewhere in a narrow band across Southern California or just off the coast in the Pacific Ocean.

Image above: Representatives of NASA, FEMA, the Jet Propulsion Laboratory, the U.S. Department of Energy’s national laboratories, the U.S. Air Force, and the California Governor’s Office of Emergency Services gathered in El Segundo, California, on Oct. 25, 2016, for a tabletop exercise simulating a possible asteroid impact in 2020. The exercise provided a forum for the planetary science community to show emergency managers how it would collect, analyze and share data about such an event. Image Credit: The Aerospace Corporation.

While mounting a deflection mission to move the asteroid off its collision course had been simulated in previous tabletop exercises, this particular exercise was designed so that the time to impact was too short for a deflection mission to be feasible -- to pose a great future challenge to emergency managers faced with a mass evacuation of the metropolitan Los Angeles area.

Scientists from JPL, Lawrence Livermore National Laboratory, Sandia National Laboratories, and The Aerospace Corporation presented predicted impact footprint models, population displacement estimates, information on infrastructure that would be affected, as well as other data that could realistically be known at various points throughout the exercise scenario.

“The high degree of initial uncertainty coupled with the relatively long impact warning time made this scenario unique and especially challenging for emergency managers,” said FEMA National Response Coordination Branch Chief Leviticus A. Lewis. “It’s quite different from preparing for an event with a much shorter timeline, such as a hurricane.”

Attendees considered ways to provide accurate, timely and useful information to the public, while also addressing how to refute rumors and false information that could emerge in the years leading up to the hypothetical impact.

“These exercises are invaluable for those of us in the asteroid science community responsible for engaging with FEMA on this natural hazard,” said NASA Planetary Defense Officer Lindley Johnson. “We receive valuable feedback from emergency managers at these exercises about what information is critical for their decision making, and we take that into account when we exercise how we would provide information to FEMA about a predicted impact.”

NASA provides expert input to FEMA about the asteroid impact hazard through the Planetary Defense Coordination Office. NASA and FEMA will continue to conduct asteroid impact exercises and intend to expand participation in future exercises to include additional representatives from local and state emergency management agencies and the private sector.

NASA’s Magnetospheric Multiscale mission, or MMS, is breaking records. MMS now holds the Guinness World Record for highest altitude fix of a GPS signal. Operating in a highly elliptical orbit around Earth, the MMS satellites set the record at 43,500 miles above the surface. The four MMS spacecraft incorporate GPS measurements into their precise tracking systems, which require extremely sensitive position and orbit calculations to guide tight flying formations.

Earlier this year, MMS achieved the closest flying separation of a multi-spacecraft formation with only four-and-a-half miles between the four satellites. When the satellites are closest to Earth, they move at up to 22,000 miles per hour, making them the fastest known operational use of a GPS receiver.

When MMS is not breaking records, it conducts ground-breaking science. Still in the first year of its prime mission, MMS is giving scientists new insight into Earth’s magnetosphere. The mission uses four individual satellites that fly in a pyramid formation to map magnetic reconnection – a process that occurs as the sun and Earth’s magnetic fields interact. Precise GPS tracking allows the satellites to maintain a tight formation and obtain high resolution three-dimensional observations.

Understanding the causes of magnetic reconnection is important for understanding phenomena around the universe from auroras on Earth, to flares on the surface of the sun, and even to areas surrounding black holes.

Next spring, MMS will enter Phase 2 of the mission and the satellites will be sent in to an even larger orbit where they will explore a different part of Earth’s magnetosphere. During that time, the satellites are anticipated to break their current high altitude GPS record by a factor of two or more.

It may be famous for hosting spectacular sights such as the Tucana Dwarf Galaxy and 47 Tucanae (heic1510), the second brightest globular cluster in the night sky, but the southern constellation of Tucana (The Toucan) also possesses a variety of unsung cosmic beauties.

One such beauty is NGC 299, an open star cluster located within the Small Magellanic Cloud just under 200,000 light-years away. Open clusters such as this are collections of stars weakly bound by the shackles of gravity, all of which formed from the same massive molecular cloud of gas and dust. Because of this, all the stars have the same age and composition, but vary in their mass because they formed at different positions within the cloud.

Hubble orbiting Earth

This unique property not only ensures a spectacular sight when viewed through a sophisticated instrument attached to a telescope such as Hubble’s Advanced Camera for Surveys, but gives astronomers a cosmic laboratory in which to study the formation and evolution of stars — a process that is thought to depend strongly on a star’s mass.

Companies across Europe are teaming up to tackle different aspects of ESA’s proposed Asteroid Impact Mission. Its detailed definition work has begun, ahead of a go/nogo decision next month.

The Asteroid Impact Mission, or AIM, is proposed for launch to the Didymos double asteroids in 2020 as part of the first-ever demonstration of a planetary defence method together with NASA’s Double Asteroid Redirection Test impactor spacecraft.

Asteroid Impact Mission

AIM will gather all the technical data required to validate impact models as DART strikes the smaller of the two bodies, while also deploying two CubeSats for complementary (and riskier) observations and putting down the Mascot-2 microlander on the Didymos’ tiny moon to probe its deep interior structure.

AIM is a mission in a hurry because asteroid Didymos continues its race for a 2022 close encounter with our planet. The onus is on industry to maintain the pace: since 2011 more than 40 companies across 15 ESA Member States have been shaping a highly innovative and fast mission.

“This wide array of activities now being carried out underlie how AIM is becoming more and more of a truly European project,” says Ian Carnelli, managing the mission for ESA.

Rosetta compared to AIM

“We’ve started our detailed definition work with industry, while the decision on full implementation of the mission will be taken at ESA’s Council of Ministers next month. This is a very important step to maintain our pace and test new approaches enabling faster mission implementation by integrating ESA, industry and payload teams.”

GMV in Madrid, for instance, is conducting important tests on the navigation camera provided by Germany’s Max Planck Institute. GMV is evaluating image-based navigation software for the mission by having the camera scrutinise imagery that ESA’s Rosetta comet chaser acquired during its 2010 flyby of the 100 km-diameter Lutetia asteroid, on the way to its Comet 67P/Churyumov–Gerasimenko.

“No two asteroids are exactly the same, and in fact the Didymos asteroids are actually too far distant for ground astronomers to know their precise surface characteristics,” explains Michael Kueppers, AIM project scientist.

Navigation camera testing

“But these Rosetta images offer a useful analogue to try out the precision navigation we will need to manoeuvre around our target ‘Didymoon’ and ultimately release Mascot-2 towards its surface within a few centimeters per second accuracy.”

“The navigation camera in question is already flying on NASA’s Dawn mission to main-belt asteroids, and has already contributed to a wealth of new scientific discoveries.” The team is also working with research consortiums who have put forward CubeSats to fly aboard AIM, ahead of a final selection to fly.

Navigation software

“It is inspiring to see the progress on the AIM design as NASA continues this innovative collaboration with ESA in the joint Asteroid Impact & Deflection Assessment,” declared Lindley Johnson, Program Executive of the Planetary Defense Coordination Office at NASA.

“Our joint concept has significant strategic benefit to both space agencies. While both missions would have substantial independent results, this collaborative endeavor will yield considerably greater benefits for international efforts on asteroid impact threat mitigation.”

AIM and CubeSats watch impact

AIM’s network of mothership, lander and CubeSats in deep space will be a world first, paving the way for new exploration architectures. AIM will also demonstrate novel technology, enabling the spacecraft to navigate autonomously around the asteroid as a self-driving spacecraft.

This stepping stone mission will allow future deep-space spacecraft to benefit from its wealth of technology demonstrations.

New information on the effects of the 30 October earthquake that struck central Italy continues to emerge as scientists analyse radar scans from satellites.

Using radar imagery from the Copernicus Sentinel-1 satellites, Italian experts have identified significant east–west displacements of the ground in the area struck by the earthquake.

An eastwards shift of about 40 cm was mapped in the vicinity of Montegallo, while a westwards shift of about 30 cm is centred in the area of Norcia.

East–west shift

Vertical displacement is also evident, with the ground sinking 60 cm around Castelluccio but rising by about 12 cm around Norcia.

The team of scientists from the Institute for Electromagnetic Sensing of the Environment of the National Research Council and the National Institute of Geophysics and Volcanology combined radar scans taken before and after the event to map centimetre-scale changes.

The team has benefited from the two Sentinel-1 satellites of Europe’s Copernicus programme. While Copernicus is led by the European Commission, ESA is in charge of developing the satellites and operates Sentinel-1.

“These impressive scientific results could be obtained very rapidly thanks to the operations concept of the Sentinel-1 mission: large scale and frequent mapping, in particular of Europe and worldwide tectonic areas, tight satellite orbit control, systematic processing of all acquired data, and open and free access of the products within few hours from observation,” said Pierre Potin, Sentinel-1 mission manager at ESA.

Vertical displacement

“In this specific case, the east–west and vertical ground displacements could be derived in less than three days after the earthquake, making use of both Sentinel-1A and Sentinel-1B and in different viewing geometries.”

Sentinel-1 is not the only satellite providing information on this recent quake: scientists are also relying on the Italian space agency’s Cosmo-SkyMed satellites, as well as satellite images from other space agencies.

The Italian peninsula is prone to earthquakes because of the continuing collision of the African and Eurasian tectonic plates. Under the Apennine mountain chain, the regional collision is causing the African slab to flex and dip under the Tyrrhenian Sea, while at the same time retreating northeastwards.

jeudi 3 novembre 2016

Humans sometimes struggle to adjust to Daylight Saving Time, but just measuring the exact length of a Saturn day is one of the big challenges for scientists on NASA's Cassini mission. Over more than a decade in Saturn orbit, Cassini's instruments have wrestled with confusing measurements to determine the planet's precise rotation rate.

The mission's final year and unprecedented trajectory will carry Cassini to unexplored regions so near to Saturn that scientists might finally answer the question:

Just how long is a day on Saturn?

Four Days at Saturn

Video above: NASA's Cassini spacecraft stared at Saturn for nearly 44 hours in April 2016 to obtain this movie showing four Saturn days. Cassini will begin a series of dives between the planet and its rings in April 2017, building toward a dramatic end of mission -- a final plunge into the planet, six months later.

Michele Dougherty used to say that measuring the length of a Saturn day was like searching for a needle in a haystack. Now she thinks the old cliché falls short. "It's more like searching for several needles that change color and shape unpredictably," she said.

Based at Imperial College, London, Dougherty is principal investigator for the magnetometer instrument (MAG) on board Cassini, studying the planet more closely than any spacecraft before. Yet Cassini's instruments can't seem to nail down something fundamental about Saturn that, for Earth, is hard to miss: the length of a day. Part of the challenge stems from what a day truly is.

When a person says, "It's been cloudy for days," they're conveying how long (that is, for how much time) the sky's been cloudy. But a day is really a description of motion, not time. The sun doesn't rise or set. Instead, the sun's apparent motion is the result of Earth spinning on its axis. And an observer need not be on Earth to figure out the length of an Earth day.

Someone in space or on another planet in our solar system could choose a distinct surface feature on Earth, such as Madagascar, then note its position and click a stopwatch. When Madagascar returns to the position it was in when the stopwatch was started, the observer could note the elapsed time. If they measured precisely enough, they would find that Earth rotates once per 23.934 hours. That's Earth's rotation rate — the very definition of a day.

Image above: This view shows Saturn's northern hemisphere in 2016, as that part of the planet nears its northern hemisphere summer solstice in May 2017. Image Credits: NASA/JPL-Caltech/Space Science Institute.

Using the same principle, Earthlings have learned the rotation rates of other planets. A day on Mercury lasts about two Earth months. And a Mars day lasts 24.623 Earth hours, barely longer than Earth's. But watching surface features does not work equally well for all planets.

When the bulk of a planet swims beneath thousands of miles of atmosphere, the challenge of clocking its rotation rate is even tougher. The swirling cloud bands on a gas planet like Saturn and Jupiter move at different rates, making it impossible to use the clouds to measure the planet's rotation rate. But even then, scientists have a couple aces up their sleeve: the planet's magnetic field and radio wave emissions.

In a planet's interior, heat causes electrically conductive fluids to move, and those currents generate a magnetic field that can extend out into space many times the diameter of the planet. On Earth and Jupiter, the magnetic north pole is tilted from each planet's rotation axis by about 10 degrees, meaning it's not aligned with the "true north" pole on either planet. If you could see Jupiter's or Earth's magnetic field from space, and you sped up time, the magnetic field would appear to wobble like a hula hoop as the planet spins. Since the magnetic field is generated in a planet's deep interior, for most planets, the field's rotation rate tells scientists the rotation rate of the planet itself. One full wobble equals one day.

We can't see magnetic fields, but instruments called magnetometers can, and radio antennas can detect radio emissions from a planet with patterns that repeat each time the planet rotates. In fact, almost as soon as radio antennas were invented, scientists figured out that Jupiter has a 9-hour and 55-minute day, according to Bill Kurth, a University of Iowa physicist and leader of Cassini's Radio and Plasma Wave Science (RPWS) team. "Jupiter is like a clock. It doesn't lose time. It doesn't gain time," he said.

But Saturn is like no other planet orbiting our sun. Its magnetic field seems to be offset from its rotation axis by very much less than a degree, so Saturn's magnetic field doesn't hula but instead appears to spin smoothly with no wobble. Scientists might then expect to observe a steady signal of magnetic strength and direction at Saturn, but they don't.

The Cassini MAG instrument has detected a signal in Saturn's magnetic field which looks like a wave in the data that repeats about every 10 hours and 47 minutes. Scientists call that regularly repeating signal a "periodicity." But this periodicity has a different value whether you're observing Saturn's northern or southern hemisphere, and it also seems to change with the seasons.

Saturn's Radio Period Crossover

Video above: This spectrogram and video show a changing pattern of radio waves from Saturn known as Saturn Kilometric Radiation, as detected by NASA's Cassini spacecraft.

The RPWS instrument has also detected periodicities, and another of Cassini's instruments, the Magnetospheric Imaging Instrument (MIMI) has observed energetic charged particles (protons, electrons, ions) being whipped around Saturn periodically by its magnetic field. "The MIMI instrument sees these blobs that move about the planet," Kurth said. But observations of the blobs, the radio emissions, and the magnetic field don't agree enough for scientists to feel they're sure about Saturn's rotation rate.

Cassini scientists didn't think Saturn's rotation rate was a puzzle they'd have to solve. "We thought we already knew, because Voyager measured it," Kurth said. Voyager data had suggested a Saturn day was about 10.7 hours. But Cassini's magnetometer measures it as a bit longer, or a bit shorter, depending on whether the spacecraft is observing Saturn's northern or southern hemisphere.

"Saturn has stymied us," Dougherty said. "Its rotation rate is somewhere between 10.6 and 10.8 hours, probably, but the signal we're seeing, we're not sure it's linked to the interior at all. All we know is that, in our MAG data, we see oscillations that are different in the north or the south, and they change over time."

One possible cause is that something in Saturn's atmosphere is disrupting or canceling out the effects of the true planetary magnetic field, Dougherty said. If that's the case, getting closer to Saturn might help.

For the final phase of Cassini's mission, the spacecraft will perform 20 orbits just outside of Saturn's main rings starting in November 2016, followed by 22 orbits flying through the unexplored space between Saturn's upper atmosphere and its innermost ring starting in April 2017. There, Cassini should have a better shot at seeing Saturn's rotation rate more clearly and resolving the mystery of Saturn's day.

"By the end of May 2017," Dougherty said, "we should know whether we'll be able to solve it."

On Oct. 19, 2016, operators instructed NASA’s Solar Dynamics Observatory, or SDO, to look up and down and then side to side over the course of six hours, as if tracing a great plus sign in space. During this time, SDO produced some unusual data. Taken every 12 seconds, SDO images show the sun dodging in and out of the frame. SDO captured these images in extreme ultraviolet light, a type of light that is invisible to our eyes. Here, they are colorized in red.

Animation above: Images from NASA’s SDO during a routine EVE cruciform maneuver show the sun dodging in and out of the frame. Animation (images) Credits: NASA’s Goddard Space Flight Center/SDO/Joy Ng.

SDO operators schedule this maneuver, one of a series of maneuvers that SDO completed on Oct. 27, 2016, twice a year to calibrate the spacecraft’s instruments. Veering motions allow scientists to assess how light travels through SDO’s instruments – whether light is reflected inside the instrument, for example – and how these instruments are changing over time.

Solar Dynamics Observatory (SDO) spacecraft. Image Credit: NASA

This particular maneuver is the EVE cruciform maneuver, designed to help SDO’s Extreme ultraviolet Variability Experiment, or EVE, take accurate measurements of the sun’s extreme UV emissions. EVE studies these emissions over time, so that we may better understand their role in influencing Earth’s climate and local space environment.

On Nov. 1, 2016, the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter observed the impact site of Europe's Schiaparelli test lander, gaining the first color view of the site since the lander's Oct. 19, 2016, arrival.

These cutouts from the observation cover three locations where parts of the spacecraft reached the ground: the lander module itself in the upper portion, the parachute and back shell at lower left, and the heat shield at lower right. The heat shield location was outside of the area covered in color. The scale bar of 10 meters (32.8 feet) applies to all three cutouts.

Schiaparelli was one component of the European Space Agency's ExoMars 2016 project, which placed the Trace Gas Orbiter into orbit around Mars on the same arrival date. The ExoMars project received data from Schiaparelli during its descent through the atmosphere. ESA reports that the heat shield separated as planned, the parachute deployed as planned but was released (with back shell) prematurely, and the lander hit the ground at a velocity of more than 180 miles per hour (more than 300 kilometers per hour).

Where the lander module struck the ground, dark radial patterns that extend from a dark spot are interpreted as "ejecta," or material thrown outward from the impact, which may have excavated a shallow crater. From the earlier image, it was not clear whether the relatively bright pixels and clusters of pixels scattered around the lander module's impact site are fragments of the module or image noise. Now it is clear that at least the four brightest spots near the impact are not noise. These bright spots are in the same location in the two images and have a white color, unusual for this region of Mars. The module may have broken up at impact, and some fragments might have been thrown outward like impact ejecta.

The parachute has a different shape in the Nov. 1 image than in the Oct. 25 one, apparently from shifting in the wind. Similar shifting was observed in the parachute of NASA's Mars Science Laboratory mission during the first six months after the Mars arrival of that mission's Curiosity rover in 2012 [http://photojournal.jpl.nasa.gov/catalog/PIA16813].

At lower right are several bright features surrounded by dark radial impact patterns, located where the heat shield was expected to impact. The bright spots appear identical in the Nov. 1 and Oct. 25 images, which were taken from different angles, so these spots are now interpreted as bright material, such as insulation layers, not glinting reflections.

China has successfully conducted the maiden launch of its Long March-5 (Chang Zhen-5) rocket on Thursday, after years of intense development to create a launch vehicle capable of orbiting heavy payload to geosynchronous and low Earth orbit. The launch occurred at 12:43 UTC on Thursday after several holds.

China Long March 5 CZ-5 launch (Illustration)

The launch of Long March-5/YZ-2 (Y1) took place at the Wenchang Space Launch Centre’s LC101 dedicated Launch Complex.

This maiden launch carried the experimental Shijian-17 complex to the geostationary orbit. The new satellite will conduct experiments using ion propulsion for station keeping.

With the strongest carrying capacity in China, the rocket will receive functional examinations and further tests before launch.

Long March 5 (CZ-5) first launch

According to the SASTIND, the Long March-5 integrates top space technologies, including non-toxic environmentally-friendly fuel and a highly stable controlling system, representing a landmark in the country's carrier rockets.

The LM-5 launch vehicle is a heavy, cryogenic liquid launch vehicle newly developed by China Aerospace Science and Technology Corporation. Following the design principal of generalization, serialization and modularization, the LM-5 uses non-toxic and non-polluting propellants such as liquid hydrogen, liquid oxygen and kerosene, etc. The modularized design can reduce launch costs and improve reliability, possessing strong adaptability and competitiveness in the market.

Shijian based satellite

The payload capability of LM-5 is 25 tons for low Earth orbit (LEO), and 14 tons for Geostationary transfer orbit (GTO), capable of launching different kinds of spacecraft, such as LEO, GTO and sun-synchronous orbit (SSO) satellites, space station and lunar probe, etc.

Sets of ridges and troughs some 1000 km north of the giant Olympus Mons volcano contain a record of the intense tectonic stresses and strains experienced in the Acheron Fossae region on Mars 3.7–3.9 billion years ago.

This scene, captured by ESA’s Mars Express on 4 May, focuses on the western part of Acheron Fossae, an isolated block of ancient terrain that covers an area about 800 km long and 280 km wide and stands up to 2 km higher than the surrounding plains.

Acheron Fossae is part of a network of fractures that radiates from the Tharsis ‘bulge’ some 1000 km to the south, home to the largest volcanoes on Mars. As the Tharsis region swelled with hot material rising from deep inside Mars as the volcanoes formed, it stretched and pulled apart the crust along lines of weakness over a wide area.

Acheron Fossae in context

This process gave rise to the classic ‘horst and graben’ system – a series of depressions (graben) bounded by faults and uplifted blocks (horsts) either side of the graben.

The pattern of cross-cutting faults seen in various places in Acheron Fossae implies the region experienced stresses from different directions over time, suggesting a complex history.

Topography of western Acheron Fossae

Part of a dominant, curved ridge that extends through the entire region is seen in the lower left of the scene. It may be an ancient graben that has since been filled with material that has flowed along it, possibly from rock-laden glaciers that were deposited in more recent cold climatic conditions, long after the graben itself formed.

Perspective view in Acheron Fossae

Acheron Fossae has been likened to Earth’s continental rift systems. Major rift zones on Earth are associated with plate tectonics, such as mid-ocean ridges that are spreading apart.

3D view in Acheron Fossae

On Mars, rifts are important for studies of the general evolution of the crust as well as the thermal evolution of the deeper subsurface.

Laser-zapping of a globular, golf-ball-size object on Mars by NASA's Curiosity rover confirms that it is an iron-nickel meteorite fallen from the Red Planet's sky.

Iron-nickel meteorites are a common class of space rocks found on Earth, and previous examples have been seen on Mars, but this one, called "Egg Rock," is the first on Mars examined with a laser-firing spectrometer. To do so, the rover team used Curiosity's Chemistry and Camera (ChemCam) instrument.

Scientists of the Mars Science Laboratory (MSL) project, which operates the rover, first noticed the odd-looking rock in images taken by Curiosity's Mast Camera (Mastcam) at at a site the rover reached by an Oct. 27 drive.

Image above: The dark, golf-ball-size object in this composite, colorized view from the ChemCam instrument on NASA's Curiosity Mars rover is a nickel-iron meteorite, as confirmed by analysis using laser pulses from ChemCam on Oct. 30, 2016. The grid of bright spots on the rock resulted from the laser pulses. Image Credits: NASA/JPL-Caltech/LANL/CNES/IRAP/LPGNantes/CNRS/IAS/MSSS.

"The dark, smooth and lustrous aspect of this target, and its sort of spherical shape attracted the attention of some MSL scientists when we received the Mastcam images at the new location," said ChemCam team member Pierre-Yves Meslin, at the Research Institute in Astrophysics and Planetology (IRAP), of France's National Center for Scientific Research (CNRS) and the University of Toulouse, France.

ChemCam found iron, nickel and phosphorus, plus lesser ingredients, in concentrations still being determined through analysis of the spectrum of light produced from dozens of laser pulses at nine spots on the object. The enrichment in both nickel and phosphorus at some of the same points suggests the presence of an iron-nickel-phosphide mineral that is rare except in iron-nickel meteorites, Meslin said.

Iron meteorites typically originate as core material of asteroids that melt, allowing the molten metal fraction of the asteroid's composition to sink to the center and form a core.

"Iron meteorites provide records of many different asteroids that broke up, with fragments of their cores ending up on Earth and on Mars," said ChemCam team member Horton Newsom of the University of New Mexico, Albuquerque. "Mars may have sampled a different population of asteroids than Earth has."

Image above: The dark, smooth-surfaced rock at the center of this Oct. 30, 2016, image from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover was examined with laser pulses and confirmed to be an iron-nickel meteorite. It is about the size of a golf ball. Image Credits: NASA/JPL-Caltech/MSSS.

In addition, the study of iron meteorites found on Mars -- including examples found previously by Mars rovers -- can provide information about how long exposure to the Martian environment has affected them, in comparison with how Earth's environment affects iron meteorites. Egg Rock may have fallen to the surface of Mars many millions of years ago. Researchers will be analyzing the ChemCam data from the first few laser shots at each target point and data from subsequent shots at the same point, to compare surface versus interior chemistry.

Egg Rock was found along the rover's path up a layer of lower Mount Sharp called the Murray formation, where sedimentary rocks hold records of ancient lakebed environments on Mars. The main science goal for Curiosity's second extended mission, which began last month, is to investigate how ancient environmental conditions changed over time. The mission has already determined that this region once offered conditons favorable for microbial life, if any life ever existed on Mars.

Curiosity was launched five years ago this month, on Nov. 26, 2011, from Cape Canaveral Air Force Station, Florida. It landed inside Gale Crater, near the foot of Mount Sharp, in August 2012.

Image above: Image above: September 2016 self-portrait of NASA's Curiosity Mars rover shows the vehicle at the "Quela" drilling location in the scenic "Murray Buttes" area on lower Mount Sharp. The panorama was stitched together from multiple images taken by the MAHLI camera at the end of the rover's arm. Image Credits: NASA/JPL-Caltech/MSSS.

The rover remains in good condition for continuing its investigations, after working more than twice as long as its originally planned prime mission of about 23 months, though two of its 10 science instruments have recently shown signs of potentially reduced capability. The neutron-generating component of Curiosity's Dynamic Albedo of Neutrons (DAN) instrument, designed for working through the prime mission, is returning data showing reduced voltage. Even if DAN could no longer generate neutrons, the instrument could continue to check for water molecules in the ground by using its passive mode. The performance of the wind-sensing capability from Curiosity's Rover Environmental Monitoring Station (REMS) is also changing, though that instrument still returns other Mars-weather data daily, such as temperatures, humidity and pressure. Analysis is in progress for fuller diagnosis of unusual data from DAN, which was provided by Russia, and REMS, provided by Spain.

The U.S. Department of Energy's Los Alamos National Laboratory in Los Alamos, New Mexico, developed ChemCam in partnership with scientists and engineers funded by the French national space agency (CNES). Mastcam was built by Malin Space Science Systems, San Diego. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Science Laboratory Project for the NASA Science MIssion Directorate, Washington, and built the project's Curiosity rover. For more information about Curiosity, visit: http://mars.jpl.nasa.gov/msl

mercredi 2 novembre 2016

For decades, NASA engineers have been key players in the design, fabrication and testing of the equipment that keeps astronauts safe in space -- on Skylab, SpaceHab and the International Space Station. Teaming with industry, they created the Environmental Control and Life Support System for the orbiting laboratory to provide clean water and air, the basic elements needed for survival.

Now a team of engineers has sent a new investigation to the station to test materials that will extend the lifespan for life-support systems on long-duration flights to Mars and beyond. When the ninth SpaceX resupply mission to the station launched July 18, it carried the Long Duration Sorbent Testbed.

"Exposure to the unique environment in the space station can change the way materials behave," said David Howard, program manager of the investigation at Marshall. "This includes what we use to filter air and water, so we need options for systems we create for the future."

Image above: The Long Duration Sorbent Testbed locker was launched to the International Space Station on July 18 to test new materials for more efficient air filtration systems that would be used on longer flights into deep space. Image Credit: NASA.

The life support system on the space station currently uses a silica gel to remove humidity or water from the air, allowing another piece of hardware to more efficiently scrub carbon dioxide from the air, keeping it from becoming toxic. After a year, that gel loses up to 75 percent of its capacity to absorb water, making it necessary to replace it relatively often. As astronauts venture father out into the solar system, they will not have the benefit of frequent resupply missions, and must consider the weight and space limitations associated with packing all the supplies they might need to bring with them on the mission.

Engineers and chemists believe that the gel loses that efficiency due to the environment inside the station and the more than 200 recorded contaminants there. The station is a very closed environment. Normal offgassing of odors from plastics and personal care products remain in the cabin air instead of being diluted by the atmosphere as here on Earth. While a specialized system scrubs these contaminants, trace amounts still remain in the cabin.

"There is a complex atmosphere on the space station," said Jim Knox, an aerospace engineer at Marshall and principal investigator for the study. "The mix of environmental contaminants alone on the station is new territory for us. As we select materials for future systems, we need to know how these materials will react to those contaminants. If we can build better filters, we can cut back on the number of replacements we would send on deep-space missions and can use that space for other payloads."

Image above: John Thomas, lead mechanical designer for the Long Duration Sorbent Testbed investigation on the International Space Station, prepares the hardware assembly at NASA's Marshall Space Flight Center in Huntsville, Alabama. The technology study will help scientists build a more efficient life support system for flights in to deep space by testing new materials to help pull water and carbon dioxide out of the air. Image Credit: NASA.

This testbed will study new substances that attract and collect molecules to determine which would be most effective for use in filters on long-duration missions. The device launched with 12 different materials to expose to the station environment. These materials were selected specifically to assist with carbon dioxide removal. The "scrubbers" on the station need water removed from the air so carbon dioxide can be more easily processed along with waste hydrogen from the oxygen generator, converting two waste products into water, a precious commodity.

When the investigation is installed on the station, it will run for a year without the need for involvement from the astronauts. Ground crews will monitor it from Earth while conducting a similar experiment with the materials in the laboratory on the ground for comparison.

The Long Duration Sorbent Testbed will not only provide data on the best material for use on long journeys in space, but will also let us know how long those materials will be effective. Both are critical points when it comes to designing the spacecraft that will carry us farther into space than ever before.

Future astronauts may return to Earth with fragments from the depths of deep space to unlock secrets of our solar system—samples of asteroids, Mars or its moons, or other destinations beyond. What precautions should be taken to maintain the scientific integrity of celestial samples and to ensure that we don’t inadvertently contaminate distant bodies with Earth-based organisms?

It’s a daunting two-part question that NASA has addressed in a report titled, “Planetary Protection Knowledge Gaps for Human Extraterrestrial Missions.” The report summarizes the proceedings of a three-day workshop in 2015 that convened global experts who investigated the top considerations for preventing biological cross-contamination of Earth and other worlds during human missions to different celestial bodies.

Planetary protection is required by the Outer Space Treaty and has far-reaching implications on human spacecraft design, operational procedures and overall mission structure.

Together with industry and international partners, NASA is developing the key technologies and capabilities to take humans farther from Earth than ever before, to advance science and technology, and to enhance our knowledge of the universe around us. For example, astronauts on the Asteroid Redirect Mission will return from cislunar space with asteroid samples that could answer questions about the formation of our solar system and our planet. Crews returning from Mars are expected to deliver samples that could tell us if Mars ever harbored microbial life, and could possibly teach us about our own planet’s past, present and future.

These extraterrestrial samples may be able to answer some of humanity’s fundamental questions, but only if they remain free of contaminants that humans or human spacecraft could potentially introduce, and don't pose a threat on their own.

Mars astrobiology

“We already have samples of Mars, and some comets and asteroids, here on Earth,” says Bette Siegel, program executive and planetary protection expert in NASA’s Human Exploration and Operations Mission Directorate. “Some comet and asteroid samples were collected by spacecraft and returned directly to Earth, but many others that have spent millions of years in space regularly fall to Earth. These are quickly contaminated by Earth organisms once they hit the ground.” Siegel noted that carefully selected samples that humans collect on Mars and return directly to Earth in special containment will be far younger and more pristine than any Mars materials analyzed in laboratories thus far.

Planetary protection experts focus on two main areas of study. “Forward contamination” refers to the transport of Earth-based microbes to other celestial bodies, a disrupting concept for scientists who are searching for signs of life in an extraterrestrial sample. “Backward contamination” refers to the possibility that extraterrestrial microbial life returned by a space mission could propagate on Earth.

The Committee on Space Research (COSPAR), an organization which is part of the International Council on Science, and which comprises national scientific unions, hosted the follow-on workshop Oct. 25-27, 2016, in Houston. After many years of successful planetary protection implementation for robotic missions, COSPAR established the first post-Apollo list of qualitative principles and guidelines in 2008 for forward and backward contamination on human missions. These guidelines, together with NASA’s own policies on planetary protection requirements, served as guiding bases for identifying the 25 knowledge gaps.

According to NASA Planetary Protection Officer Catharine Conley, the collaborative goal of planetary protection experts is to inform spacecraft design and mission protocols compliant with the qualitative and eventual quantitative requirements. NASA plans to pursue development of a NASA Procedural Requirements (NPR) document that will ensure future spacecraft are designed to those requirements.

“Effective requirements, which NASA describes in NPRs, are essential to ensuring that planetary protection protocols are included in mission design from the start,” says Conley. “It's critical to establish the quantitative requirements now, that engineers need to follow while designing human-rated systems for travel beyond Earth orbit.”

Outcomes of the recent COSPAR meeting could potentially have significant influence on global contributors to human spaceflight. Gerhard Kminek, the European Space Agency’s Planetary Protection Officer and the Chair of COSPAR’s Panel on Planetary Protection acknowledged the strong role that NASA will play in the global collaboration, “NASA and COSPAR hope that by closing the knowledge gaps outlined in the report of the previous workshop, we will be able to establish clear quantitative guidelines on planetary protection that will lead to eventual international consensus standards for human missions beyond Earth orbit and particularly in support of a collaborative journey to Mars.”

From 1998 to 2011, five different space agencies representing 15 countries assembled the International Space Station, the largest structure ever built in space. Today humans are still living and work in the orbital laboratory. November 2, 2016 marks the 16th anniversary of continuous human presence onboard.

2. The Expedition 1 crew arrives

Expedition 1 Commander William Shepherd fist pumps and celebrates with his cosmonaut crewmates Sergei Krikalev and Yuri Gidzenko as they appear on camera for the first time on November 2, 2000.

3. September 11, 2001

Expedition 3 Commander Frank Culbertson was the only American living off the planet on September 11, 2001. He captured his view of the fateful day from the space station.

The space station offers a unique vantage for observing Earth. Station crews can observe and collect camera images of events as they unfold which can play an important role in helping emergency responders know what areas are most in need during natural disasters.

4. The robotic arm builds the station piece by piece

The Japanese Experiment Module, or Kibo, is installed to the space station on June 3, 2008. Kibo means “hope” in Japanese, and it is the largest single space station module.

5. First 6-person crew

The first 6 person crew on the space station gathers for a press conference in May 29, 2009. Because it was comprised of astronauts from NASA, CSA, ESA, JAXA, and Russia, this was the first and only time all international partners were represented on the space station at the same time.

6. Commercial industry visits station

Currently, commercial companies SpaceX and Orbital ATK make regular trips to deliver cargo to the space station. NASA’s Commercial Crew Program is working with commercial companies to develop and operate spacecraft to launch people to the International Space Station.

7. Olympic Torch goes on a spacewalk

Russian Cosmonauts Sergey Ryazanskiy and Oleg Kotov bring the Olympic torch outside the space station during a spacewalk on November 9, 2013. The torch traveled to the station as part of the Olympic torch relay ahead of the 2014 Winter Olympics in Sochi, Russia.

8. Testing fire in space

Astronaut Reid Weisman captured a floating sphere of fire observed during the Flex-2 experiment on space station on July 18, 2014. The findings may lead to better engines here on Earth.

9. Aurora

Aurora are one of the astronauts' favorite views from the station. The spectacle is a result from energized particles in the atmosphere from steady solar winds or giant eruptions known as coronal mass ejections.

10. Sunrise

Astronauts see 16 sunrises and sunsets every day as the station zooms around the Earth every 90 minutes.

11. Water Bubbles

In microgravity, liquids float freely in spherical form, but when in contact with other objects, surface tension dominates its shape.

12. Spacewalking

Astronauts Terry Virts and Barry “Butch” Wilmore capture the first GoPro footage of a spacewalk on February 25, 2015. To date, 195 spacewalks have been performed to build and maintain the space station.

13. DNA Sequencing

For the first time ever, DNA was successfully sequenced in microgravity as part of the Biomolecule Sequencer experiment performed by NASA astronaut Kate Rubins aboard the space station. With a way to sequence DNA in space, astronauts could diagnose an illness, or identify microbes growing in the station and determine whether or not they represent a health threat.

14. Milky Way

When passing over the "night" side of Earth, the Milky Way galaxy is subtly visible from the station.

15. Astronauts eat first space-grown lettuce

Astronauts Scott Kelly, Kjell Lindgren, and Kimiya Yui taste lettuce that had been grown and harvested in space by NASA for the very first time on August 10, 2015.

16. First expandable space habitat

The Bigelow Expandable Activity Module is the first expandable habitat to be sent to space. It was expanded on May 28, 2016. Expandable habitats are designed to take up less room on a spacecraft, but provide greater volume for living and working in space once expanded.